1/*	$NetBSD$	*/
2
3#include <tommath.h>
4#ifdef BN_MP_ADD_C
5/* LibTomMath, multiple-precision integer library -- Tom St Denis
6 *
7 * LibTomMath is a library that provides multiple-precision
8 * integer arithmetic as well as number theoretic functionality.
9 *
10 * The library was designed directly after the MPI library by
11 * Michael Fromberger but has been written from scratch with
12 * additional optimizations in place.
13 *
14 * The library is free for all purposes without any express
15 * guarantee it works.
16 *
17 * Tom St Denis, tomstdenis@gmail.com, http://libtom.org
18 */
19
20/* high level addition (handles signs) */
21int mp_add (mp_int * a, mp_int * b, mp_int * c)
22{
23  int     sa, sb, res;
24
25  /* get sign of both inputs */
26  sa = a->sign;
27  sb = b->sign;
28
29  /* handle two cases, not four */
30  if (sa == sb) {
31    /* both positive or both negative */
32    /* add their magnitudes, copy the sign */
33    c->sign = sa;
34    res = s_mp_add (a, b, c);
35  } else {
36    /* one positive, the other negative */
37    /* subtract the one with the greater magnitude from */
38    /* the one of the lesser magnitude.  The result gets */
39    /* the sign of the one with the greater magnitude. */
40    if (mp_cmp_mag (a, b) == MP_LT) {
41      c->sign = sb;
42      res = s_mp_sub (b, a, c);
43    } else {
44      c->sign = sa;
45      res = s_mp_sub (a, b, c);
46    }
47  }
48  return res;
49}
50
51#endif
52
53/* Source: /cvs/libtom/libtommath/bn_mp_add.c,v */
54/* Revision: 1.4 */
55/* Date: 2006/12/28 01:25:13 */
56